This invention relates to improvements in variable pitch diameter pulleys, and more particularly, to torque-responsive pulleys.
The general system of a speed- and torque-responsive variable ratio belt drive is well known in the art, as shown, for example, in the following U.S. Pat. Nos. 2,678,566, 2,711,103, 3,616,706, 3,625,079, 3,699,827, 3,800,608, 3,842,637 and 4,102,214. In such drive systems, primary control of the drive ratio is generally provided by a speed-responsive pulley driven by the engine, or other rotary power source, and secondary control is provided by a torque-responsive driven pulley which, in response to increased torque in the drive train, applies feed-back belt tension to counteract the speed response and increase the drive ratio over that which the speed-responsive mechanism tends to provide.
Under certain conditions, as where the driven member suddenly encounters an obstacle, commonly referred to as shock loading, the torque-responsive pulley may open too far resulting in the drive belt becoming lodged too deep in the pulley, or bringing about damaging levels of belt slippage. In either event, belt failure may be immediate, or at the very least, premature.
Accordingly, it is an object of the present invention to provide a torque-responsive pulley which overcomes impulsive responses to shock loading.
Other objects of this invention will become apparent as the description progresses.